An optoelectronic oscillator (OEO) including a drift compensation circuit is provided. The OEO includes a set of optical domain components communicatively coupled with a set of RF domain components. The RF domain components include a mode selection filter, a phase locked loop (PLL) and a drift compensation circuit communicatively coupled between the mode selection filter and the PLL. The mode selection filter provides a mode selection result to the drift compensation circuit. The drift compensation circuit phase modulates the mode selection result in a vector based coordinate system to maintain a drift compensated mode selection result within a locking bandwidth of the PLL, and to minimize phase shifting from accumulating phase drift. The PLL detects a phase difference between the drift compensated mode selection result and a reference signal, for use in maintaining the PLL in a phase lock with the reference signal, in particular over wide operational temperature ranges.

An atomic oscillator includes a gas cell, a semiconductor laser, and a frequency modulation signal generation section (such as a frequency transform circuit) which generates a frequency modulation signal for causing the semiconductor laser to generate frequency-modulated light including a resonance light pair (first-order sideband light pair) that causes an electromagnetically induced transparency phenomenon in metal atoms. When a modulation index of the frequency modulation signal, by which a first-order differential value of oscillation frequency deviation of the atomic oscillator becomes 0, is regarded as a first modulation index, the modulation index is within a range between a second modulation index, which is smaller than the first modulation index, with which the oscillation frequency deviation is 0 and a third modulation index, which is greater than the first modulation index, with which the oscillation frequency deviation is 0.

An optoelectronic oscillator (OEO) including a drift compensation circuit is provided. The OEO includes a set of optical domain components communicatively coupled with a set of RF domain components. The RF domain components include a mode selection filter, a phase locked loop (PLL) and a drift compensation circuit communicatively coupled between the mode selection filter and the PLL. The mode selection filter provides a mode selection result to the drift compensation circuit. The drift compensation circuit phase modulates the mode selection result in a vector based coordinate system to maintain a drift compensated mode selection result within a locking bandwidth of the PLL, and to minimize phase shifting from accumulating phase drift. The PLL detects a phase difference between the drift compensated mode selection result and a reference signal, for use in maintaining the PLL in a phase lock with the reference signal, in particular over wide operational temperature ranges.

There is described a device for generating electromagnetic field oscillation in a RF device or cavity. The device generally has a photo-diode configured for receiving a laser pulse train and emitting a first electrical signal based thereon, the first electrical signal having a plurality of frequencies; and a harmonics selector configured to output a second electrical signal having one or more frequency of the first electrical signal, the one or more frequency being selected in a manner for the output to generate the electromagnetic field oscillation in the RF device or cavity.

Embodiments of the present disclosure disclose an optoelectronic oscillator including an optical chip and a microwave chip. The optical chip is implemented by fabricating different optoelectronic devices on an integrated optical substrate, comprising: a laser assembly; a mode selection device coupled to the laser assembly, and configured to receive the laser and perform mode selection; an optical delay module coupled to the mode selection device; and a detector coupled to the optical delay module. The microwave chip is a microwave integrated circuit formed by fabricating microwave elements on a semiconductor substrate, comprising: a microwave processing circuit configured to receive microwave signal and perform signal processing; a coupler coupled to the microwave processing circuit, and configured to provide a part of the microwave signal to a phase shifter and output the other part thereof; and a phase shifter configured to feed the phase-shifted microwave signal to the laser assembly.

A system for correcting a duty cycle comprises a digital quadrature generator circuit, a frequency doubler circuit, a first duty cycle correction circuit coupled between the digital quadrature generator circuit and the frequency doubler circuit, and a second duty cycle correction circuit coupled between the digital quadrature generator circuit and the frequency doubler circuit. The first duty cycle correction circuit comprises a first stacked duty cycle correction circuit and the second duty cycle correction circuit comprises a second stacked duty cycle correction circuit.

A semiconductor device that generates or detects terahertz waves includes a semiconductor layer that has a gain of the generated or detected terahertz waves; a first electrode connected to the semiconductor layer; a second electrode that is arranged at a side opposite to the side at which the first electrode is arranged with respect to the semiconductor layer and that is electrically connected to the semiconductor layer; a third electrode electrically connected to the second electrode; and a dielectric layer that is arranged around the semiconductor layer and the second electrode and between the first electrode and the third electrode and that is thicker than the semiconductor layer. The dielectric layer includes an area including a conductor electrically connecting the second electrode to the third electrode. The area is filled with the conductor.

The present invention relates to a radiofrequency oscillator comprising an optical resonator being a ring waveguide allowing the propagation of a first wave in a first direction and of a second wave in a second direction, the second direction being opposite to the first direction, and the resonator comprising an active optical medium generating a first optical line from the first wave and a second optical line from the second wave, the resonator being in contact with a part made of a material featuring a magneto-optic effect, an applier of external magnetic field of adjustable intensity on the resonator generating a frequency offset between the first wave and the second wave, and a processing circuit converting the beat between the two optical lines in a radiofrequency signal.

Embodiments of the present disclosure disclose an optoelectronic oscillator including an optical chip and a microwave chip. The optical chip is implemented by fabricating different optoelectronic devices on an integrated optical substrate, comprising: a laser assembly; a mode selection device coupled to the laser assembly, and configured to receive the laser and perform mode selection; an optical delay module coupled to the mode selection device; and a detector coupled to the optical delay module. The microwave chip is a microwave integrated circuit formed by fabricating microwave elements on a semiconductor substrate, comprising: a microwave processing circuit configured to receive microwave signal and perform signal processing; a coupler coupled to the microwave processing circuit, and configured to provide a part of the microwave signal to a phase shifter and output the other part thereof; and a phase shifter configured to feed the phase-shifted microwave signal to the laser assembly.

The present invention relates to a radiofrequency oscillator comprising an optical resonator being a ring waveguide allowing the propagation of a first wave in a first direction and of a second wave in a second direction, the second direction being opposite to the first direction, and the resonator comprising an active optical medium generating a first optical line from the first wave and a second optical line from the second wave, the resonator being in contact with a part made of a material featuring a magneto-optic effect, an applier of external magnetic field of adjustable intensity on the resonator generating a frequency offset between the first wave and the second wave, and a processing circuit converting the beat between the two optical lines in a radiofrequency signal.